The placement of the hose clamp could make a difference. I usually put the hose clamp about 1/4 inch from the end of the hose. Also be certain that the hose is pushed ALL the way onto the adapter.
Are you certain the water is leaking from the flex hose and not the adapter that screws into the valve port on the top of the filter? I had a very small leak where the adapter screwed into the port but solved that by reinstalling the Teflon tape. Just and idea to look into.
Good luck.
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